In the therapy of treatment-resistant depression lithium augmentation has been shown
to be an effective method. About 50% of lithium-augmented patients respond to this
strategy (Bauer et al., 2003). Nevertheless, mechanisms and predictors for the clinical
efficacy of lithium augmentation are still unknown, although genetic factors (for
example by modulating serotonergic neurotransmission) are discussed to play an important
role for the treatment response (Serretti et al., 2002; Serretti et al., 1999). Results
of our own study group suggest an influence of a polymorphism in the 5HTTLPR (Stamm
et al., submitted). This study investigates the association between genetic polymorphisms
of tryptophane-hydroxylase type 2 (TPH2) and the response to lithium augmentation
treatment in 49 patients with treatment-resistant depression. The Cox-Regression-Survival-Analysis
showed no significant difference between the three TPH2 genotypes. Further results
including a bigger sample are pending and expected for summer 2005. We also await
results on the possible association with other genetic polymorphisms (for example
G-protein beta–3). Furthermore, possible interactions of these genetic polymorphisms
and their common effect on treatment response to lithium augmentation shall be investigated.
